Problem Description

Takahashi has created $ N $ problems for competitive programming. Each problem is numbered from $ 1 $ to $ N $, and the difficulty of problem $ i $ is represented by an integer $ d_i $ (higher values indicate greater difficulty).

Takahashi is trying to classify these problems into two types by choosing an integer $ K $:

• Problems with difficulty $ K $ or higher are for "ARC"
• Problems with difficulty below $ K $ are for "ABC"

How many ways are there to choose an integer $ K $ such that the number of problems for "ARC" and "ABC" are equal?

Input Format

The input is given from the standard input in the following format:

$ N $ $ d_1 $ $ d_2 $ $ ... $ $ d_N $

Output Format

Output the number of ways to choose an integer $ K $ such that the number of problems for "ARC" and "ABC" are equal.

Sample Input and Output

Sample Input #1

6
9 1 4 4 6 7

Sample Output #1

2

Sample Input #2

8
9 1 14 5 5 4 4 14

Sample Output #2

0

Sample Input #3

14
99592 10342 29105 78532 83018 11639 92015 77204 30914 21912 34519 80835 100000 1

Sample Output #3

42685

Notes/Hints

Constraints

• $2 \leq N \leq 10^5$
• $ N $ is even.
• $1 \leq d_i \leq 10^5$
• All inputs are integers.

Sample Explanation 1

When $ K = 5, 6 $, problems $ 1, 5, 6 $ are for "ARC" and problems $ 2, 3, 4 $ are for "ABC", satisfying the condition. Therefore, the answer is $ 2 $ ways.

Sample Explanation 2

There may be cases where no choice of integer $ K $ can make the number of problems for "ARC" and "ABC" equal.

见题面 Input 部分

见题面 Output 部分